Impact fuze for a spinning projectile



Nov. 21, 1967 F. BERGER IMPACT FUZE FOR A SPINNING PROJECTILE Filed Feb.21, 1966 Fig.2

2 .6 xx a a 2 b t 4 4 B 9 v Inventor: Fm fZ Berger United States Patent3 tClaims. Cl. 102-79 ABSTRACT OF THE DESCLOSURE A percussion fuze forspinning projectiles having means operative by centrifugal force toplace the fuze in firing position as to the slidable firing pin andhaving a rotor adapted to be adjusted into an ignition position by thecentrifugal force but held in non-ignition position during transport bya second rotor safety device.

The invention relates to an impact fuze for a spin ning projectile, thefuze having a rotor adapted to be righted into an ignition positionunder the effect of centrifugal force, and having an axially slidablestriker pin bearing, in the transport position, against .a supportingsurface of the rotor and securing it against movement to an ignitionposition.

In a known impact fuze for a spinning projectile having a rotor adaptedto be righted into an ignition position by centrifugal force, the rotorhas a supporting surface disposed transversely of the axis of the fuzeand which is arranged as a bearing for movable blocking bodies of alocking device which are adapted to be brought out of contact with therotor. The locking device is provided, in turn, with movable releasemembers for terminating the locking of the rotor and securing theblocking bodies against displacement when the rotor is in the transportposition, the release members and the blocking bodies operating insuccession and thereby releasing the rotor for righting or erection, therotor being merely moved by friction.

A method of that kind for securing the rotor is not satisfactory,however, when greater bore safety is required, bore safety being anindication of the distance the projectile must travel before the fuze isready for operation. For this reason, this known impact fuze justmentioned has been improved so that the rotor is able to right itselfonly by means of parts of the locking device. This righting into theignition position is achieved because the blocking element, which bearson the supporting surface of the rotor in the transport positionthereof, is removed in the ignition position of the rotor, and, at thesame time, contact between the striker pin of the impact fuze and therotor is prevented during the righting movement thereof. In other words,a safety or securing element is displaced on firing and a shorteningthereof thereby occurs, so that after the acceleration of the projectileis complete the blocking members are lifted away from the supportingsurface of the rotor by centrifugal force. The blocking members engagealso below a shoulder of the striker pin and lift the latter while theblocking members move beyond the shoulder. As a result, the rotor cannow right itself into the ignition position. In this position the boresafety is at an end.

The blocking members may consist of four small blocks provided withconical surfaces or it may be a one-piece slide which is pushed aside bythe centrifugal force and releases the striker pin in the process.

In this known impact fuze, the blocking members determine the boresafety, i.e. as the blocking members fiy outwards they not only releasethe rotor for righting, but at the same time also free the striker pin.Particularly great bore safety cannot be achieved in this way.

In another known impact fuze, the transport position of a centrifugalrotor is ensured by a striker pin which can be displaced on thelongitudinal axis of the fuze. This is done by means of a flattenedportion of the cylindrical surface of the rotor, against which thestriker pin is supported. Between the striker pin, which extends into arecess in the rotor, and the tip of the fuze there are two rotor safetydevices, first a fusible pellet mounted in the tip of the fuze and whichcan be melted by the heat of the ram pressure due to the forwardmovement of the projectile and by which the striker pin is preventedfrom moving axially and thereby releasing the rotor, and, second, twoarms articulated to the striker pin and having roller-shaped centrifugalbodies, which tend to draw the striker pin forward under centrifugalforce and thereby release the rotor. After the projectile has left thebarrel of the weapon from which it is fired, the pellet melts owing tothe heat of the ram pressure, and the striker pin is drawn forward bythe force of the centrifugal bodies and the rotor is able to rightitself into the ignition position. The bore safety is thereby at an end.

If it is borne in mind that it must be possible to carry out firing overa temperature range of 30 C. to +30 C., this gradient of 60 C. amountingto about one half of the melting temperature of the pellet, whichconsists of Woods metal, then it becomes clear how dependent thecommencement of the melting of the pellet is on the air temperature.Since, however, the bore safety is at an end with the drawing along ofthe striker pin which follows immediately thereon, the bore safety willbe at an end close in front of the barrel if melting of the pelletbegins prematurely.

Finally, there is also known an impact fuze with a rotor safety devicein which the locking means holding the rotor in the transport positionconsists of a split ring which can be expanded radially by centrifugalforce and releases the rotor to such an extent that the latter is ableto right itself from the transport position into the ignition position.

On release of the rotor, a blocking slide located in front of a flashhole in the fuze is moved aside, so that an ignition path from the rotorto the projectile charge is now exposed.

Owing to the fact that the centrifugal force only has to spread thesplit ring, the bore safety is very small in this known impact fuze.

The common drawback of all known fuzes is that the construction of thevarious safety devices can be achieved only with constructional elementswhich are complicated and costly and/or unsafe in operation.

Therefore, the problem underlying the invention is to produce an impactfuze for a spinning projectile in which a rotor adapted to be rightedinto the ignition position by centrifugal force is held in the transportposition by an axially slidable striker pin which bears against asupporting surface of the rotor, the fuze being distinguished by animproved bore safety which is independent of external influences, inspite of the fact that its internal arrangement consists of only a fewrobust parts.

According to the invention, there is provided a second rotor safetydevice which consists of a blocking device Whose effect is terminated aknown time after the first safety device has become inoperative.

The blocking device may consist of a coiled band adapted to expandradially and which is pretensioned and embraces the rotor over its fullwidth when the rotor is in the transport position. Instead of the coiledband,

it is also possible to employ other blocking elements which also delaythe righting of the rotor.

By way of example an embodiment of the invention will now be describedin detail with reference to the drawings, in which:

FIG. 1 shows in longitudinal section an impact fuze with aself-destroying arrangement and a coiled band in the transport position,and

FIG. 2 shows in longitudinal section the impact fuze illustrated in FIG.1 after the bore safety is at an end.

The impact fuze illustrated consists of two main structural systems,namely a self-destroying system and the bore safety device system.

The self-destroying system is mounted in the front part of a fuze casing1 and is followed at the rear by the bore safety device system. Theself-destroying system, which is known per se, consists of a sleeve 2with a bearing surface 3, a ball carrier 4 with balls 5, and a spring 6.These parts surround a fuze plunger 7, which has its upper (as seen inFIG. 1) end located behind a diaphragm 8 and extends at its lower endinto a central bore in the ball carrier 4. The lower part of the ballcarrier 4 is in the form of a striker pin 4a with a projecting strikerpoint 4b.

In the transport position of the fuze which is shown in FIG. 1, thestriker point 4b extends into a blind bore 9a in a rotor 9, which is, inturn, mounted in a cavity formed between the sleeve 2 and the fuze body10. A percussion cap 12 is inserted in a central bore 11 in the rotor 9.

The lower end face of the striker pin 4a bears on a flat portion 13 ofthe rotor 9, the latter having also another fiat portion 14 extendingparallel to the axis of the fuze and the width of which correspondsapproximately with the distance between the sleeve 2 and the fuze body10. This flat portion 14 is surrounded by a coiled spring band 15 whichis given a slight initial tension, which enables the band to form acompact spring bundle. The coiled band 15 is housed in a cage 17arranged at right angles to the axis of the fuze and symmetrically withrespect to the axis of the rotor, the external diameter of the cage 17being such that the internal diameter of the coiled band 15, when it isopened out as it expands outwardly, is larger than the outer diameter ofthe closed coil. Below the rotor 9 there is a central bore 16 in thefuze body.

The fuze operates in the following manner:

In the transport position shown in FIG. 1, the rotor 9 has its axissymmetry in an inclined position with respect to the axis of the fuze.In this position, it is held both by the percussion pin 4a, which issubject to the effect of the spring 6, and by the coiled band 15, sothat the striker point 412 cannot penetrate into the percussion cap 12in the rotor 9 and nor can transmission of ignition take place, even inthe event of the occurrence of premature ignition of the percussion cap12.

Under the effect of the acceleration of the projectile which occurs onfiring, the entire internal arrangement of the fuze remains in thetransport position shown in FIG. 1. Towards the end of the accelerationperiod, i.e. when the projectile has emerged from the mouth of thebarrel of the weapon from which it has been fired and the centrifugalforce takes full effect owing to the spin of the projectile, the balls 5are moved outwards along the bearing surface 3 of the sleeve 2, theballs pushing the axially displaceable parts, consisting of the ballcarrier 4 and the fuze plunger 7, towards the upper end of the fuze inopposition to the force of the spring 6. In this process, the strikerpin 4a is lifted away from the flat surface 13 and the striker point 4bis lifted out of the blind bore 9a, so that the rotor 9 is no longersecured from this side. The righting or erection of the rotor 9,however, is delayed by the coiled band 15, which begins to fly outwardas the centrifugal force becomes operative, until the full peripheralsurface of the rotor tiU 9 passes through the innermost turn of theoutwardflying coiled band 15. The rotor 9, which is likewise subjectedto the effect of the centrifugal force, rights itself out of itsinclined position until its axis of symmetry coincides with the axis ofthe fuze.

As shown in FIG. 2, when the second safety device has also becomeinoperative, the range of flight designated as the bore safety marginhas now been completed. If the fuze now strikes the target, the tip ofthe fuze and the fuze plunger 7 are forced in, and the percussion cap12, which is now freely accessible in the rotor 9, is pierced by thestriker point 4b and the percussion cap in turn causes detonation of thedetonator (not shown) and thereby of the bursting charge via bore 16.

It is also possible to employ other safety devices instead of a coiledband 15, as long as they provide the requisite delay in the righting ofthe rotor.

In the self-destroying system, the ascended balls 5 hold thepretensioned spring 6 over a part of the trajectory under the effect ofthe centrifugal force. If, however, in the further course of the flightof the projectile, the speed of rotation of the projectile steadilydecreases, there comes a moment when the axial component of thecentrifugal force becomes smaller than the force of the spring 6, andthe latter is able to cause the striker point 4b to move forward againstthe percussion cap 12 by way of the ball carrier 4, so as to cause inthis way the self-destruction of the projectile at a predetermined pointalong its trajectory.

I claim:

1. A percussion fuze for spinning projectiles comprising a casing havinga front part and a rear part, a sleeve secured in the rear part of thecasing and having a bearing surface, a ball carrier with balls mountedslidably in the casing and in the sleeve, and having a striker pinsecured thereon, a fuze body secured in the rear part of the casing andspaced from the sleeve, a rotor mounted to rotate between the fuze bodyand the sleeve and having a coiled band around the rotor and having apercussion cap therein; and a fuze plunger slidably mounted in thecasing and extending into the sleeve, said rotor being normally held ininoperative position by the coiled band and when the projectile is firedcentrifugal spinning force will act on the band to hold the rotor in anunarmed position for a predetermined period of time so that when theballs in the ball carrier force the latter away from the rotor thestriker pin will be in a position to plunge into the percussion cap whenthe projectile strikes a target.

2. A percussion fuze according to claim 1, in which a cage is formedbetween the sleeve and the fuze body to accommodate the coiled band sothat the latter will be arranged symmetrically in relation to a rotoraxis.

3. A percussion fuze according to claim 1, in which a cage is formedbetween the sleeve and the fuze body to accommodate the coiled band sothat the latter will be arranged symmetrically in relation to a rotoraxis, and in which the outside diameter of the cage is dimensioned sothat when the band is open, the inner diameter of the coil is largerthan the outside diameter of the closed coil.

References Cited UNITED STATES PATENTS 2,656,793 10/1953 Howell lO2-8O2,682,835 7/1954 Meister 10279 2,782,717 2/1957 Burri et al. 102-79 X2,921,527 1/1960 Guerne 102-79 3,033,115 5/1962 Guerne 102-79 X3,112,704 12/1963 Schaadt 10279 X 3,136,253 6/1964 Kulesza et al. 1OZ79BENJAMIN A. BORCHELT, Primary Examiner.

SAMUEL FEINBERG, Examiner.

G. H. GLANZMAN, Assistant Examiner

1. A PERCUSSION FUZE FOR SPINNING PROJECTILES COMPRISING A CASING HAVINGA FRONT PART AND A REAR PART, A SLEEVE SECURED IN THE REAR PART OF THECASING AND HAVING A BEARING SURFACE, A BALL CARRIER WITH BALLS MOUNTEDSLIDABLY IN THE CASING AND IN THE SLEEVE, AND HAVING A STRIKER PINSECURED THEREON, A FUZE BODY SECURED IN THE REAR PART OF THE CASING ANDSPACED FROM THE SLEEVE, A ROTOR MOUNTED TO ROTATE BETWEEN THE FUZE BODYAND THE SLEEVE AND HAVING A COILED BAND AROUND THE ROTOR AND HAVING APERCUSSION CAP THEREIN; AND A FUZE PLUNGER SLIDABLY MOUNTED IN THECASING AND EXTENDING INTO THE SLEEVE, SAID ROTOR BEING NORMALLY HELD ININPOPERATIVE POSITION BY THE COILED BAND AND WHEN THE PROJECTILE ISFIRED CENTRIFUGAL SPINNING FORCE WILL ACT ON THE BAND TO HOLD THE ROTORIN AN UNARMED POSITION FOR A PREDETERMINED PERIOD OF TIME SO THAT WHENTHE BALLS IN THE BALL CARRIER FORCE THE LATTER AWAY FROM THE ROTOR THESTRIKER PIN WILL BE IN A POSITION TO PLUNGE INTO THE PERCUSSION CAP WHENTHE PROJECTILE STRIKES A TARGET.